Introduction: The emergence of collaborative robotics highlights the need to align technological design with human experience at work. In human-robot interaction (HRI), fluency, the smooth, adaptive, and coordinated interplay between partners, is a key determinant of collaborative quality. A critical aspect of fluency is motor coordination, namely the temporal alignment of actions between agents. Despite its relevance, little empirical evidence has examined how robot motion design shapes this coordination in applied settings.


Purpose: This study investigates whether human-like versus machine-like robot movements affect motor coordination with a human partner during collaborative assembly tasks, and whether this effect varies with the degree of interdependence between partners' actions.


Method: Twenty-two participants engaged in assembly tasks with a cobot under four conditions: high/low interdependence × human-like/machine-like motion. Human and cobot joint kinematics were tracked using a machine learning-based pose estimation model, focusing on the human right wrist and the cobot's end-effector. Coordination was assessed via self-reports and behavioral data (i.e., cross-correlation CC and mutual information MI between time series, as indicators of synchronous coupling). Repeated-measures ANOVAs tested the effect of movement style and interdependence on coordination.


Results: Results evidenced significant effects of condition on coordination indices. Post-hoc comparisons indicated that human-like kinematics in high interdependence tended to produce higher coordination than machine-like kinematics or low interdependence conditions, although adjusted contrasts reached only marginal significance.


Conclusions: Human-inspired kinematics foster greater motor coordination, particularly when collaboration requires high interdependence. These results suggest that biologically-inspired movements enhance fluency, and potentially improve trust and acceptance in human-robot collaboration. Future research should assess these aspects and broaden the focus to additional psychological and organizational outcomes, positioning motor compatibility as a key lever for sustainable and human-centered robotic design.